1. Field
The present invention relates to compositions for breast cancer diagnosis comprising a material that specifically binds to a polymeric immunoglobulin receptor (PIGR) protein or a fragment thereof, and a method of diagnosing a breast cancer using said compositions.
2. Description of the Related Art
Microvesicles are small membranous vesicles that exist in or are secreted from various types of cells. Microvesicles secreted from cells include: (i) exosomes, which are vesicles having a diameter from about 30 to about 100 nm; (ii) ectosomes (also called shedding microvesicles (SMVs)), which are vesicles that are released directly from the plasma membranes and have a diameter from about 50 to about 1000 nm; and (iii) apoptotic blebs, which are vesicles secreted from dying cells that have a diameter from about 50 to about 5000 nm.
It has been confirmed through electron microscopy that exosomes are not directly released from a plasma membrane, but rather originate from specific intracellular regions called multivesicular bodies (MVBs), and are then released into the extracellular environment as exosomes. Although it has not yet been clearly determined which molecular mechanisms and pathways are involved in the generation of exosomes, it is known that red blood cells, other various kinds of immune cells, including B-lymphocytes, T-lymphocytes, dendritic cells, blood platelets, and macrophages, and even tumor cells, are able to produce and secret exosomes when in vivo. Exosomes are also known to be separated and excreted from different cell types depending on whether they are in normal states, pathologic states, or abnormal states.
Exosomes comprise surface proteins, which may be used for detection and analysis of the status (e.g., health) of individual cells or organisms. The status of cells or organisms may comprise a disease state, for example, cancer, hereditary diseases, heart diseases, or neuronal diseases (e.g., schizophrenia).
Existing breast cancer diagnosis methods are invasive and thus, are painful to patients. Additionally, existing breast cancer diagnosis methods are very costly, which may prohibit individuals that cannot afford such methods to have less frequent checkups. High accuracy blood tests that utilize blood protein markers for early stage breast cancer diagnosis are not currently available. Circulating tumor cells (CTCs), which comprise blood protein markers useful for the diagnosis of breast cancer, are produced in the metastatic stages of breast cancer, which is often too late to be of use to an individual.
Therefore, a need remains for less invasive compositions and methods for the early diagnosis and selective screening of breast cancer utilizing specific blood markers.